×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Displaying STate of an Analog Output on Test kit (0-10v and 0-20mA)

Displaying STate of an Analog Output on Test kit (0-10v and 0-20mA)

Displaying STate of an Analog Output on Test kit (0-10v and 0-20mA)

(OP)
Looking at chucking a trainign/testing kit together for some of our kits.

Having the idea of using a small display to represent the analog value that we choose to output through one of the controllers analog outputs.

Problem is, we are unaware of the technology available to diplay these values when the outputs are changed from the aforementioned modes or output, and if possible, recognise the change and switch accordingly.

Does anyone know of anything that may be suitable?

RE: Displaying STate of an Analog Output on Test kit (0-10v and 0-20mA)

No. I do not know about any such instrument. But it could be done - no problem really.

You can use the fact that a 4-20 mA circuit always has a compliance voltage that is at least 24 V and that the minimum current in a functioning circuit is 4 mA.

Now, if you connect a high impedance instrument, it will show compliance voltage. The high voltage (more than 10 V) will switch the instrument to current mode (switching in a load resistor and subtracting 4 mA). It has to latch in that state or you will see it switch to and from current mode indefinitely.

If this instrument is connected to a 0-10 V signal, it will stay in voltage mode. Load resistor and offset not active.

That's how I would do it. But there are probably other ways as well.

Gunnar Englund
www.gke.org

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources